The seriously injured were admitted to a hospital at Udaypur in Rajasthan, they added.
"When we were working at the dry cooler of a soya plant around 8 PM last night, it blew off with a loud bang sparking a fire that created a commotion," said a worker Mohanlal.
"Maintenance work of the dry cooler was underway and the wielding work going on under it, and prima facie this possibly caused the blast," Sub Divisional Magistrate (SDM) Aditya Sharma said.
Plant General Manager M P Vishwakarma said the accident was result of the blast in the gas cylinder which sparked off the fire.